Question 321: AC fundamentals

Question

A coil of self inductance L is connected in series with a bulb B and an a.c. source. Brightness of the bulb decreases when

Accepted Answer

When iron rod is inserted, the coil magnetizes the iron rod increasing the magnetic field.
$	herefore \quad$ Inductance ( L ) of coil increases.
$$\mathrm{V}=\mathrm{L} \frac{\mathrm{di}}{\mathrm{dt}}$$
$	herefore \quad$ Voltage drop across the coil increases
i.e. voltage drop at bulb decreases.
$	herefore \quad$ Brightness of bulb decreases.

Answer

frequency of a.c. source is decreased.

Answer

number of turns in the coil is reduced.

Answer

a capacitance of reactance $\left(\mathrm{X}_{\mathrm{L}}-\mathrm{X}_{\mathrm{C}}\right)$ is included in the same circuit.

Answer

an iron rod is inserted in the coil.

AC fundamentals

A coil of self inductance L is connected in series with a bulb B and an a.c. source. Brightness of the bulb decreases when

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